One rough but familiar instance of the same effect, from the same cause, we can all see in the marked distinction between the pastoral, the agricultural, and the manufacturing classes in any nation, though their other conditions be the same. On the clear line of argument that functions and organs are developed by use, that what we use most is developed most, and that the daily processes of supplying economic needs are the processes that we most use, it follows that, when we find special economic conditions affecting any special class of people, we may look for special results, and find them. In view of these facts, attention is now called to a certain marked and peculiar economic condition affecting the human race, and unparalleled in the organic world. We are the only animal species in which the female depends on the male for food, the only animal species in which the sex-relation is also an economic relation. With us an entire sex lives in a relation of economic dependence upon the other sex, and the economic relation is combined with the sex-relation. The economic status of the human female is relative to the sex-relation. It is commonly assumed that this condition also obtains among other animals, but such is not the case. There are many birds among which, during the nesting season, the male helps the female feed the young, and partially feeds her; and, with certain of the higher carnivora, the male helps the female feed the young, and partially feeds her. In no case does she depend on him absolutely, even during this season, save in that of the hornbill, where the female, sitting on her nest in a hollow tree, is walled in with clay by the male, so that only her beak projects; and then he feeds her while the eggs are developing. But even the female hornbill does not expect to be fed at any other time. The female bee and ant are economically dependent, but not on the male. The workers are females, too, specialized to economic functions solely. And with the carnivora, if the young are to lose one parent, it might far better be the father: the mother is quite competent to take care of them herself. With many species, as in the case of the common cat, she not only feeds herself and her young, but has to defend the young against the male as well. In no case is the female throughout her life supported by the male. In the human species the condition is permanent and general, though there are exceptions, and though the present century is witnessing the beginnings of a great change in this respect. We have not been accustomed to face this fact beyond our loose generalization that it was “natural,” and that other animals did so, too.